materialism, in philosophy, a widely held system of thought that explains the nature of the world as entirely dependent on matter, the fundamental and final reality beyond which nothing need be sought. Certain periods in history, usually those associated with scientific advance, are marked by strong materialistic tendencies. The doctrine was formulated as early as the 4th cent. B.C. by Democritus, in whose system of atomism all phenomena are explained by atoms and their motions in space. Other early Greek teaching, such as that of Epicurus and Stoicism, also conceived of reality as material in its nature. The theory was later renewed in the 17th cent. by Pierre Gassendi and Thomas Hobbes, who believed that the sphere of consciousness essentially belongs to the corporeal world, or the senses. The investigations of John Locke were adapted to materialist positions by David Hartley and Joseph Priestley. They were a part of the materialist development of the 18th cent., strongly manifested in France, where the most extreme thought was that of Julien de La Mettrie. The culminating expression of materialist thought in this period was the Système de la nature (1770), for which Baron d'Holbach is considered chiefly responsible. A reaction against materialism was felt in the later years of the 18th cent., but the middle of the 19th cent. brought a new movement, largely psychological in interpretation. Two of the modern developments of materialism are dialectical materialism and physicalism, a position formulated by some members of the Logical Positivist movement. Closely related to materialism in origin are naturalism and sensualism.

historical materialism: see dialectical materialism.

dialectical materialism, official philosophy of Communism, based on the writings of Karl Marx and Friedrich Engels, as elaborated by G. V. Plekhanov, V. I. Lenin, and Joseph Stalin. In theory dialectical materialism is meant to provide both a general world view and a specific method for the investigation of scientific problems. The basic tenets are that everything is material and that change takes place through "the struggle of opposites." Because everything contains different elements that are in opposition, "self-movement" automatically occurs; the conflict of opposing forces leads to growth, change, and development, according to definite laws. Communist scientists were expected to fit their investigations into this pattern, and official approval of scientific theories in the USSR was determined to some extent by their conformity to dialectical materialism (see Lysenko, Trofim Denisovich). Use of these principles in history and sociology is sometimes called historical materialism. Under these doctrines the social, political, and intellectual life of society reflect only the economic structure, since human beings create the forms of social life solely in response to economic needs. Men are divided into classes by their relations to the means of production—land and capital. The class that controls the means of production inevitably exploits the other classes in society; it is this class struggle that produces the dynamic of history and is the source of progress toward a final uniformity. Historical materialism is deterministic; that is, it prescribes that history inevitably follows certain laws and that individuals have little or no influence on its development. Central to historical materialism is the belief that change takes place through the meeting of two opposing forces (thesis and antithesis); their opposition is resolved by combination produced by a higher force (synthesis). Historical materialism has had many advocates outside the Communist world.

In metaphysics, the doctrine that all of reality is essentially of the nature of matter. In the philosophy of mind, one form of materialism, sometimes called central-state materialism, asserts that states of the mind are identical to states of the human brain. In order to account for the possible existence of mental states in creatures that do not share the human nervous system (e.g., octopuses and Martians), proponents of functionalism identified particular mental states with the functional or causal roles those states play with respect to other physical and mental states of the organism; this allows for the “multiple realizability” of the same mental state in different physical states. (Strictly speaking, functionalism is compatible with both materialism and non-materialism, though most functionalists are materialists.) As a form of materialism, functionalism is “nonreductive,” because it holds that mental states cannot be completely explained in terms that refer only to what is physical. Though not identical with physical states, mental states are said to “supervene” on them, in the sense that there can be no change in the former without some change in the latter. “Eliminative” materialism rejects any aspect of the mental that cannot be explained wholly in physical terms; in particular, it denies the existence of the familiar categories of mental state presupposed in folk psychology. Seealso identity theory; mind-body problem.

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Philosophical approach expressed through the writings of Karl Marx and Friedrich Engels, and later by Georgy Plekhanov, Vladimir Ilich Lenin, and Joseph Stalin, the official philosophy of communism. Its central tenet, borrowed from Hegelianism, is that all historical growth, change, and development results from the struggle of opposites. (In philosophical terms, a thesis is opposed by its antithesis, which results in a synthesis.) Specifically, it is the class struggle—the struggle between the capitalist and landowning classes, on the one hand, and the proletariat and peasantry, on the other—that creates the dynamic of history. The laws of historical dialectics are seen to be so powerful that individual leaders are of little historical consequence. Originally conceived as operating primarily in the social, economic, and political realm, the principle was extended in the 20th century to the scientific realm as well, with major effects on Soviet science. Marx and Engels stated their philosophical views mainly in the course of polemics and brief historical studies; there is no systematic exposition of dialectical materialism.

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